An eating noise. Usually used with capital letters to emphasize how delicious something is; this word is used in chatrooms more often than not. It serves the same purpose as nom.
"I'm eating mashed potatoes! *NYOM*"
The sound a hippo makes when it is in the mood to mate
As the male (hippo) approached the female (hippo), he seemed to say, ''nyom nyom nyom''. To which she replied by shaking her hippo hips and spread her legs and they did the hippo hustle